110. There are four kinds of supernatural merit: (a) condign merit in the stricter sense, that is merit which arises from justice, and which presupposes no favor on the part of the rewarder. In this sense Christ merited, since even the grace which made His merits supernatural was due to Him as the God-Man; (b) condign merit in the less strict sense, that is merit which arises indeed from justice, but presupposes a favor on the part of the rewarder. In this way the righteous merit before God, since their works confer a right to their own reward, while the grace which enables them to perform their works is a divine favor; (c) congruous merit in the stricter sense, that is merit which arises not from justice (since there is no equality between the work and the reward), but from the fitness of things, because the person who merits is a friend of God. In this way all who are in the state of grace can merit spiritual goods for others; (d) congruous merit in the wide sense, that is merit which arises from the liberality of God, who answers a good work as if it were a prayer. In this way the good works done by sinners can be said to merit conversion for them.
111. The second kind of merit mentioned above—i.e., condign merit in the less strict sense—is that with which we are chiefly concerned here, since it is the kind of merit that must be found in human acts in order that they may lead man to a supernatural reward. A fuller treatment of merit is found in Dogmatic Theology in the Question on Grace.
112. The conditions requisite for the kind of merit now in question are: (a) that the work done be human, that is, free, morally good, and supernatural (i.e., proceeding from sanctifying grace and divine charity); (b) that the one who merits be in the wayfaring state (i.e., that he have not already passed to final reward or punishment), and that he be in the state of grace; (c) that God has promised a reward for the work done. From the statements made above, it follows that all the human and morally good works of those who are in the state of grace possess condign merit.
113. The objects of condign merit—i.e., the rewards promised by God for the good works done for Him in this life—are: (a) an increase of sanctifying grace; (b) the right to eternal life; (c) the attainment of eternal life, if the one who merits dies in grace; (d) an increase of glory.
114. The conditions for the merit of strict congruity are the same as those given above (112), except the promise made by God, which is not required. Examples of this kind of merit are the sanctity of the Blessed Virgin, which made her deserve more than others to be the Mother of God, and the conversion of St. Paul through the merits of St. Stephen.
115. For the merit of wide congruity it is necessary that the work done be morally good. Examples of this kind of merit are the sighs of the ancient Patriarchs, as obtaining the coming of the Messiah. The just man can merit with the merit of wide congruity the following: (a) his own conversion after a future fall; (b) his final perseverance; (c) temporal goods.
Art. 5: THE PASSIONS
(_Summa Theologica_, I-II, qq. 22-48.)
116. Having discussed the acts proper to man, we shall now speak of the passions, which are common to both man and beast.
117. Definition.—The passions—also called the emotions, affections, or sentiments—are acts of desire; but, unlike the acts of the will, they are directed, not to good apprehended by the higher knowing power of the intellect, but to good apprehended by the lower knowing power of sense and imagination. They are defined as: acts or movements of the sensitive appetite which arise from the representation of some good in the sense faculties, and which produce some transformation in the body, such as palpitation of the heart, increased circulation of the blood, paleness, blushing, etc.